London has plenty of pedestrian crossings, but they're unmarked, at least not in the same way - a stop line for cars before the lights, sure - except for 'zebra crossings', which look different, have different rules (no traffic lights and cars must give way to pedestrians) and would never be called a 'crosswalk'.

I suppose they just don't need to be, because not using one isn't 'jaywalking'. If there's too much traffic you identify a safe crossing by zebra stripes (or flashing beacon) or traffic lights or island.

When reCaptcha first asked me to identify the 'crosswalks', sure, I guessed it must be the road markings. But I just (still, to this day) select all the road markings that aren't obviously just centre direction seperating lines. I might get loads wrong, no idea.